Machine gun firing rate control mechanism



Hg. 31, 1948. w, GOLDEN 2,448,024

MACHINE GUN FIRING RATE CONTROL MECHANISM Filed March 15, 1945 3 Sheets-Sheet 1 will? uinul M1 2 a4 24 d 83a INVENTOR LLM 7: 601, DEW

ATTORNEY Aug. 31, 1948. w. T. GOLDEN MACHINE GUN FIRING RATE CONTROL MECHANISM 3 Sheet t 2 Filed Ma 15' ToR ATT EY Aug. 31, 1948. w. T. GOLDEN 2,448,024

MACHINE GUN FIRING RATE CONTRQL MECHANISM I Filed March 15, 1945 5 Sheets-Sheet 3 FIG. 8.

I? ummnll 44 43 42 39 J/E' H6113.

INVENTOR WILL/A T. GOLDEN BY W W W ATTORNEY Patented Aug. 31, 1948 MACHINE GUN FIRING RATE CONTROL MECHANISM William T. Golden, United States Navy Application March 15, 1945, Serial No. 582,967

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 7 Claims.

This invention relates to devices for controlling the rate of fire of machine guns, and more particularly to a novel device for reducing the firing rate of such guns.

One of the methods of fire control used with machine guns, and particularly with antiaircraft machine guns, is the so-called tracer'method in which the gunner directs the fire of the machine gun by watching the paths of the tracer bullets fired by the gun, and moves the gun so as to bring the paths of the tracers onto the target. Ammunition belts or magazines for such guns usually are loaded with one tracer for every three or four rounds, the other rounds being incendiary, ball, and /or high-explosive rounds. In training antiaircraft gunners in the use of the tracer method of fire control, the usual target is a sleeve pulled by an airplane at which fire is directed from the gun. If the cartridge belts or magazines are loaded as described above, the gunner being trained benefits only from the tracers in the belt, and the other two or three rounds which accompany each tracer serve only to space the tracers and are of negligible value in training the gunner. Hence, it would be desirable to load the ammunition belt with tracers only, but for the fact that, with the gun firing at its normal rate of fire, the frequency of the tracers seen by the gunner would then be two or three times greater than in actual combat so that the value of the training would be decreased due to the dissimilarity of the training and combat conditions. It would also be desirable to dispense with the nontracer rounds that are fired in target practice in order to conserve ammunition, as these rounds are of value in training only as a means of spacing the tracer bullets at the proper intervals.

It is an object of this invention, therefore, to provide a novel device for decreasing the rate of fire of a machine gun. By the use of such a device, in training gunners, the ammunition belt or magazine is loaded entirely with tracers and the rate of fire of the gun is decreased to such an extent that tracers are fired at the sameintervals as if the gun were firing at its full rate of fire and the belt or other ammunition container were loaded in the usual ratio of one tracer to every three or four rounds.

Besides it advantages for use in antiaircraft target practice, the new machine gun cyclic rate control is useful in aircraft target practice where the pilot and gunners are able to learn the use of the tracer method of fire control without wasting large quantities of ammunition. In such uses, the aircraft machine guns are provided with the new device and their magazines loaded with tracers only.

Another important use of the new device in aircraft is in connection with the well known practice of firing scare shots at an enemy plane. For instance, a pilot who sees an enemy aircraft attacking a friendly plane but finds himself too far from the combat to attack the enemy plane efiectively may fire scare shots at the enemy in the hope that the tracers from his guns will divert the enemys attention from the friendly plane long enough to permit the ally to escape or obtain a position of advantage from which to attack the enemy craft. By carrying one machine gun loaded with tracers only and utilizing the new firing rate reducing device, the gunner firing the scare shots is able to save ammunition and to carry a larger load of tracers which he fires at the same rate as though they were fired from a machine gun loaded in the usual manner, thus increasing the realism of the attack in the mind of the enemy pilot.

Another use for a standard aircraft machine gun provided with the device and loaded with tracers only is as a sighting means for rockets. By selecting a firing range at which the trajectories of the machine gun and the aircraft rockets coincide, the gunner can fire spotting tracers as a guide to the release point for the rocket.

A further use for the device is in the training of pilots to assist them in overcoming the nervousness which arises when enemy fire is encountered for the first time. Tracer loaded machine guns on the ground and in other aircraft are fired toward the green pilot so as to intentionally miss him but nevertheless to acquaint him with the feeling that comes to one under fire. As the tracers are the only rounds which the pilots sees, the machine guns are loaded with tracers only and are provided with the new cyclic rate reducer so as to save ammunition and lessen the danger of hitting the pilot or his plane while still simulating the tracer firing rate of a machine gun loaded in the usual manner.

Another object of the invention is to provide a device of the type referred to above which is attachable to the gun with a minimum of modification to the gun, and which does not change in any way the method of operation of the gun by the gunner.

Another object of the invention is to provide a device of the above-described nature which permits immediate return of the gun to its full rate of automatic operation without detaching the reducing device attached to the breech of an, Oerlikon 20 mm. machine gun with parts of the breech mechanism omitted for clarity;

Fig. 2 is an exploded view of the control devices with parts of the mechanism broken away. for. clarity;

Fig. 3 is an exploded perspective view of: part? of the device showing elements of the breech mechanism of the gun;

Fig. 4 is a cross sectional view taken .onJine' 4-4 of Fig. 1;

Fig. 5 is a side elevation of the control device partially in section;.

Fig. 6 is a detailed view of part of the device with the trigger in its firing position;

Fig. 7 isa detailed perspective view of a portion of the mounting bracket ofithe device;

Fig.8 is adetailed view of'the-trigger with the interlock knob positioned toconnect the trigger. directly to the firing mechanism of the gun Fig. 9 is a cross sectional'view'taken on-line 9-9- of Fig. 6;

Fig. 10 is an exploded/detailed view of .theinter' lock knob;

Fig. 11is afrontelevationalview of the controldevice mounted on the gun ShOWil'l-g the gun frame in section;

Fig, 12 is a diagram ofthe electrical circuit for intermittently actuating the control solenoid; and.

Fig. 13 is-a sideelevationview, partly in section, of a modification of the control device utilizing a spring motor-and cam.

In the drawings, the deviceds' shown inuse with a mm. Oerlikonmachine gun, but it is to be understoodthat the device'is not limited to me with this gun.- The. control device is mounted on. the gun by means of a mounting bracket 26 which surrounds the. gun frame. on

three sides and isheld-inplace-by a screw 2| and.

a spacer 22. Th'gframe also includes a solenoid supporting plate 23 and a side plate 24. Screws.

25 are provided on the bottomv side of the supporting. bracket and are adapted to b tightened against a projection 26 on the lower side of the gun to secure the supportingbracket ZO-agaihst movement relative to the gun.

The upper rear corner of plate 2lhas an opening 21 therein around which is an outwardly extending circular fiangeZB on which isrotatably mounted a modified trigger 29. The modified trigger which is the only'part of the gunwhich must be changed when the. new rate controlling device is used, has a forwardly and outwardly extending switch operating arm 30, and is held in place by a screw 83a mounted in openin 84a in the plate 24 and passing through arcuat opening 85 in the trigger, the screw'also serving to define the limits of movement of" the trigger;

A disc shap'ed trigger adapterSI has a hollow axial extension3'la which receives one end of trigger retaining bolt 32 and is locked" thereto by means of a' cotter pin 33. Extension 3la and bolt 32 extend through the opening 2-! and through'the wall 21a of thebreech mechanism housing, the bolt 32 carrying thetrigger intermediate-lever'ii't in the interior mechanism of is-rotatable on the same axis as the trigger.

An'Lint8I'1OCk2'kn0b"18 is pivotally mounted on trigger 29 by means of pin 19, a spring 80 being mountedron thepin '19 so as to press against the headfll of the 'pinand against the interlock knob torpermitalimited outward movement of the interlock knob and to urge the knob into engagement witlr the trigger 29. The pin 19 is driven with a.force. fit.in.a-hole in the trigger 29. and byvthatmeans is rigidly held in position. A positioning pin 82 is mounted on the knob for cooperation with holes .83. and B4 in the trigger. By pulling outwardly on the interlock knob sufliciently. to. disengage pin 82 from engagement with" hole 83 or M, the knobmay be moved to and locked in its inoperativecondition in which pin 82 engages opening 83, or its. interlocking position inwhich pin 8ZIJengages opening 84 in the trigger: In theinterlocking position (Fig. 8), the knob engages'shoulder 35 oftrigger adapter 3| so thatmovement of'trigger29 to the firing position rotates trigger'adapter 3| and trigger re.- taining' bolt 32" to initiate full automatic operation of'the gun as will be discussed presently.

Alink38 is attached to trigger 29 near its lower end by an outwardlyextending pin 40 carried by the-'triggenand a cotter pin 4|. The link extends'forwardly through an opening in a projection 42 on the plate'24, and through a coil spring 43' which bears against the projection 42 and against a washer 44 fastened'on the forward end of link 39f Spring 43'urges the trigger toward its forward or nonfinng position.

The"aforementionedswitch operating arm 30 cooperates'with' a-plunger 45' to operate a switch 46'whiclrismounted'on the plate 24 by screw 41. Rearward movement of'the trigger 29 moves arm 30 downwardly to depress the plunger and close the'switch, the purpose of which will be explained presently.

The" solenoid supporting bracket 23 supportsthe'soenoid lli'anda socket 49 to which is connected an electrical circuit which transmits intermlttent electrical impulses to the solenoid through wire 5llwhich runs directly to the solenoida'nd'wire 56 which connects to the solenoid through switch 46'. The armature 52 of the solenoidis' connected by means of a connecting arm 53, a lock nut 54, pin'55, and cotter pin 56, to one end of link 51, the other end of which lies in the groove in the periphery of the trigger adapter and is connected thereto by means of a retaining pin 58.

The circuit for transmitting intermittent impulses to the solenoid may be of'any suitable type,

' oneof which is diagrammed in Fig. 12 of the drawing and will now be described. A direct currentpower supply 59 such as a battery is connected across terminals 60 and 6|. A switch 590: is provided between power supply 59 and terminal" 60. Terminal 60 is connected in series through variable'resistances' 62 and 63 to the coil of "a relay 64; the coil of the relay also being connected to terminal 6!. A condenser 65 is connected in parallel with the coil of the relay 64. A shunt connection 66 across resistance. 63 pernits cutting resistance 63 out of the circuit be- ;ween terminal 66 and the relay coil 64 when :witch 61 in the shunt connection is closed. Reay 64 simultaneously operates a pair of switches 38 and 69. The closing of switch 68 by operation )f the relay 64 closes a circuit through a resistance Ill to discharge condenser 65. The closing of switch 69 by the operation of the relay 64 :ompletes a circuit from terminal 60 to solenoid 38 through wire 5| and switch 46, th wire 50 :onnected to the solenoid being connected to terminal 6|. An arc-preventing condenser H is provided in parallel with the switch 69 in order to prolong the life of the switch.

The operation of the circuit is as follows: With switch 59a closed and switch 61 in open position, the current flows from the source 59 to terminal 60, through resistances 62 and 63, through relay coil 64 and back to terminal 6|, meanwhile charging condenser 65. When the relay 64 is sumciently energized, it simultaneously closes switches 68 and 66. The closing of switch 68 discharges the condenser 65 through the resistance I and causes a sufiicient drop in the current passing through coil 64 to deenergize the relay. As soon as the relay 64 is deenergized and switch 68 opens, the condenser 65 again becomes charged and when the charge becomes sufiiciently high, the coil 64 is energized again to close switches 68 and, 69. The provision of the resistances 62 and 63 in series with the condenser 65 provides a predetermined time delay in the operation of relay 64, the values of resistances 62 and 63 and of the condenser 65 determining the rate of operation of the relay 64. By closing switch 61, the resistance 63 is shunted out of the circuit resulting in a change in the ratio between the the resistance in the circuit and the capacitance of condenser 65 so that by operation of switch 61, the rate of operation of the relay 64 may be controlled, The closing of switch 69 by relay 64 as described above completes a circuit from terminal 60 through wire and switch 46 to the solenoid to operate the solenoid when switch 46 is closed. When condenser 65 discharges and switch 69 is opened by the deenergization of the relay 64, the solenoid 48 is deenergized. The results of the operation of solenoid 48 will be described presently. The above-described circuit represents only one of several convenient circuits for intermittently energizing solenoid 48, and it is to be understood that any other circuit for actuating the solenoid periodically may be used without departing from the spirit of the invention.

Before describing the operation of the firing rate controlling mechanism, it may be well to describe briefly the operation of the firing mechanism of the gun so that the relation of the firing rate controlling device and the gun mechanism will be clear. The rear end of trigger hook 12 which is pivoted at T3 to a nonrecoiling part of the gun housing is urged downwardly by spring 714 so that its downwardly extending forward portion 15 tends to move upwardly out of the path of pivoted and spring-pressed sear 16 carried by the rear end of the reciprocating breech bolt 16a. Engagement of the trigger hook at 15 with shoulder T! on the sear retains the breech bolt in its cocked position. Counterclockwise rotation of trigger intermediate lever 34, as seen in Fig. 3 to its firing position moves a series of levers (not shown) which normally retain the forward portion of trigger hook 12 in a depressed condition. This permits movement of the forward portion of trigger hook 12 under the infiuence of spring 14 to release sear l6 and permit forward motion of the bolt and subsequent firing of the gun. As long as the trigger intermediate lever 34 is retained in its firing position,

the forward portion of the trigger hook remains raised and the gun continues firing until the ammunition supply is exhausted. Upon clockwise rotation of the trigger intermediate lever, the forward portion of the trigger hook is moved downwardly so as to engage the pivoted sear on its next rearward movement and retain the sear in its retracted position as shown in Fig. 3, thus halting the firing of the gun.

The operation of the firing rate control is as follows: With the interlocking knob 18 in the inoperative position, as shown in Figs. 1 and 5, rearward movement of trigger 26 against spring 43 depresses arm 30 into contact with the switch operating plunger 45 which closes switch 46. The closing of switch 46 connects solenoid 48 into the circuit as shown in Fig. 12 so that the solenoid 48 receives intermittent electrical impulses therefrom. Operation of the solenoid by the intermittent impulses reciprocates rod 53 and oscillates the trigger adapter 3| to operate intermittently the firing mechanism of the gun. This in effect, changes the machine gun operation into rapid-fire, single-shot operation, one round being fired every time solenoid 4a operates the firing mechanism of the gun.

If for any reason it is desired to utilize the full firing rate of the machine gun, for example, in case of a sudden enemy attack during target practice, the interlock knob '56 may be pulled outwardly and rotated to its interlocking position shown in Fig. 8 as explained above, thereby connecting trigger 29 directly to trigger adapter 3! so that operation of the trigger initiates automatic action of the gun which then continues firing until the trigger is released or until the ammunition supply is exhausted. During such a period of fire at the enemy, the electrical circuit need not be disconnected but may be ignored as its operation has no effect on the gun when the trigger is connected directly to the firing mechanism of the gun.

For an example of the values of the various' electrical components of the circuit shown in Fig. 12, if a 28-volt D. C. voltage is supplied to terminals 69 and 6!, resistance 62 is approximately 75 ohms, resistance 63 is approximately 25 ohms, condenser 65 is approximately 6,000 microfarads, and condenser H is approximately 30 microfarads. By using these electrical components, the rate of operation of the solenoid 48 and consequently the rate of fire of the gun is approximately 150 or 225 rounds per minute, depending upon the position of switch 61.

In Fig. 13 is shown a modification of the invention utilizing a spring motor 81 in place of a solenoid for actuating the gun firing mechanism. The spring motor 81 has a rotating barrel 81a and rotates a cam 88 which cooperates with a cam follower Sil carried by lever arm 96. The barrel B'la of the spring motor is notched at 88a,

for cooperation with a spring-pressed latch pawl 89 which is operated by arm 30 of trigger 29. The lever arm 90 is pivoted at one end to the side plate (not shown) and is connected at its other end to connecting arm 53 which operates trigger adapter 3|.

In operation, the spring motor device is simi lar to the solenoid-operated device except that the reciprocation of connecting arm 53 results 7 from motion transmitted to lever arm at by cam 88 as the spring motor rotates the cam. Arm 38 of the trigger is depressed: on movement of the triggerto, the firing position, causing pawl 8.3; to, move clear of notches 88a to permit rotationof; the spring motor and firing of the gun. Release of the trigger permits, pawl 89 to reengage; the notches 88a to halt the firing of the gun, The interlock knob 78 is provided for the same purpose as in the solenoid operated device.

The invention herein described may be manufactured and used, by or for the Government of the United States of America for governmental purposes without the, payment of any royalties thereon or therefor.

Iclaim:

1. In a machine gun having an inherently automatic firing mechanism,,a, device for controlling thelfiring rate of the gun comprising, in combination, a trigger; normally inoperativeto control automatic operation of said firing mechanism, a spring motor under the control of said trigger, cam means driven by said spring motor for operating said'firingmechanism at regular intervals and at a rate lower than the rate of automatic firing, and selective means for suspending the function of the cam means and rendering the trigger operative to control automatic operationof said firing mechanism.

2. In a machine gun having a high-rate recoiloperated firing mechanism, a device for controlling the firing rate of said mechanism, comprising initially dormant power means for producing uniformlyspaced power impulses at a rate lower than the high rate of the firing mechanism, transfer means through which said impulses are transmitted to said firing .mechanism to substitute for the inherent high firing rate, a dual-purpose trigger, meansresponsive to one motion of the trigger to animate said power means thus through said transfer means to alter the rate of automatic recoil operation and actuate said firing mechanism at the corresponding low'rate thereby accomplishing one of the purpose of the trigger, and means adjustably mounted on the trigger initially disconnected from the transfer means, being settable to couple the trigger with a portion of the transfer means, imparting a subsequent motion of the trigger directly to the firing mechanism to restore automatic firing, thereby bypassing the power means and most of the transfer means and accomplishing the other purpose of the trigger.

3. A machine gun firing, mechanism including a breech bolt reciprocable by recoil at an inherently high cyclic firing rate under control of a manually operable trigger, a trigger hook for holding the breech bolt-after each recoil, and a trigger intermediate lever for normally automatically displacing the trigger hook; in combination with said mechanism, av trigger adapter having means connecting it with the trigger intermediate lever,

power driven. means independent of said mechanism butmounted on the gun and operatively connected with the trigger adapter, said independent means being operable at a fixed rate lower than thatat which the breech bolt tends to reciprocate, and manually operable means to start and stop, the power driven means, there-- by; actuating the trigger intermediate lever at a correspondingly. fixed low rate and converting the firing mechanism from automatic rapid repetitive firing to consecutive relatively slow single-shot-operation.

4. A machine gunhaving'firing mechanism including a trigger intermediate lever and a high- 1 pulse-producing rate reciprocable recoil-operated breech bolt; controlled thereby; in combination, a firing rate.con-

trol device for reducing the reciprocation of the,

tive swinging of the trigger intermediate lever and a resulting slow single shot operation of the breech bolt, and means mounted on the trigger for couplingthe trigger directly to the intermediate lever to hold said lever upon movement of the trigger to said position, thereby bypassing the transfer means and resulting in automatic rapid operation of the breech bolt.

5. In a machine high-rate firing mechanism including a trigger intermediate lever, transfer means fixedly connected at one end with said lever, a circuit-closing trigger swung loosely from the other end of the transfer means, a device for reducing the firing rate of the gun comprising a solenoid, an interrupting circuit containing the solenoid being operable upon closure by the trigger by electrical impulses in said circuit at a predetermined rate lower than the high-rate firing of said mechanism, said solenoid having a movable core linked to the transfer means, and selective means mounted on part of the trigger and operative thereon to either connect or disconnect the trigger to or from the transfer means, making the firing mechanism operative either at its high rate or at the reduced rate of the solenoid upon identical manual operation of the trigger.

6; In a machine gun having firing mechanism including a trigger intermediate lever movable to a position to cause firing, a trigger adapter fixedly connected with the intermediate lever, being operable to hold said lever in firing position for automatic repetitive firing at a rapid rate and, alternatively to successively move said lever into. and out of firing position for reduced-rate successive single shot firing, a solenoid connected in,

a periodically impulsed electrical circuit and having its core linked to the trigger adapter, .a switch to control said circuit, a manual trigger loose anduncoupled with respect to the trigger adapter, being swingable independently of the trigger adapter to close the switch and thus energize the solenoid to produce successive single shot firing, and an interlock knob carried by part of the trigger, be,- ing settable to locking position against, the, trigger adapter to fixedly couple the trigger to the,

trigger adapter for automatic repetitive firing upon a subsequent swing of the manual trigger.

7. A machine gun firing mechanismincluding a breech bolt reciprocable by recoil at an inherently high cyclic firing rate, a trigger hook for holding the breech bolt after each recoil, and a trigger in... termediate lever for normally automatically displacing the trigger hook; in combination with said mechanism, a supporting bracket having a. circular flange, a trigger freely swung on said flange and having an operating arm, a trigger adapter. journaled in the flange and, bein fixedly connected with the trigger intermediate lever, im-

power driven means mounted on gun having an inherently- 9 10 the bracket, said means including an element UNITED STATES PATENTS which when actuated by the operating arm upon swinging of the trigger initiates the operation of Number Name te the power driven means, transfer means connect- 814,854 Lehmann Mar. 13, 1906 ing the power driven means with the trigger 5 1,352,391v Green Sept. 14, 1920 adapter to cause the impulses of the power driven 1,518,498 Furrer Dec. 9, 1924 means to repeatedly swing the trigger interme- 2,057,169 Swenson Oct. 13, 1936 diate lever, and interlock means mounted on the 2,225,599 Gaty et al. Dec. 17, 1940 trigger being adjustable to interlock the trigger 2,347,481 Hooven Apr. 25, 1944 and trigger intermediate lever to enable bypass- 10 2,380,455 Lippert et a1 July 31, 1945 ing the impulses of the power driven means. 2,381,916 Lippert Aug. 14, 1945 WILLIAM T. GOLDEN.

REFERENCES CITED The following references are of record in the 15 file of this patent: 

